The physicochemical properties of Korean rice flour cultivars (Saemimyeon [SM], Hanareum No. 4 [HA], and Milyang No. 328 [MY]) with different amylose contents were analyzed and the effects of rice flour blending on their physicochemical property changes were investigated in this study. The swelling power of three different cultivars was similar at 60oC, but MY showed significantly enhanced swelling power at 80oC compared to SM and HA. In the pasting profile, MY showed significantly lower final and break-down viscosities than SM and HA due to its weak granular rigidity. In the case of the 1:1 blending of SM-MY and HA-MY, the measured values of swelling power and solubility were greatly decreased at 80oC, and the setback and final viscosity were significantly increased compared to their predicted arithmetic average values, showing the non-additive effects of blending. For the dynamic viscoelastic properties, SM-MY and HA-MY showed significantly decreased G’ and increased k’ and tanδ, compared to their predicted average values. In conclusion, the selected rice flour blends had non-additive effects on swelling power, solubility, pasting, and dynamic viscoelastic properties. These results showed the feasibility of the rice flour blending to diversify the physicochemical properties of rice flour for better processing suitability.

The relationship of in vitro starch digestibility and gel strength was investigated at various concentrations (10-30%) of rice cultivars with different amylose contents (27.9, 17.9, and 5.2%). As the rice flour concentration increased, predicted glycemic index decreased, but gel strength increased regardless of amylose contents. Gel strength correlated strongly with amylose content, whereas in vitro starch digestibility was more highly affected by rice flour concentration than by amylose contents. Moreover, the impact of degree of gelatinization on in vitro starch digestibility of high amylose rice was also examined in terms of structural features and rheological properties. The digestion rate of fully gelatinized flour was 1.7 times higher than that of native flour, while the disrupted structure with a different gelatinization degree during starch digestion was visually demonstrated through the X-ray diffraction and molecular distribution analysis. The rice flour changed from an A-type to a V-type pattern and showed difference in crystalline melting. The low molecular weight distribution increased with increasing degree of gelatinization during starch digestion. The apparent viscosity also increased with degree of gelatinization. These results demonstrated that the starch digestibility of rice was more affected by concentration than by amylose content, as well as by the degree of gelatinization due to structural difference.

In-vitro food mastication has been simulated by incorporating size reduction process, followed by incubation with human saliva. However, they do not suffice to simulate the actual oral breakdown process where disruption by mastication (chewing) and wetting/lubrication by salivation take place simultaneously. In this study, in-vitro oral digestion of rice gels with different amylose contents was simulated by instrumentally performing mastication and salivation. The hardness of artificial saliva-treated rice gels was distinctly lowered with increasing chewing cycles and the rice gels with high amylose contents showed the highest degradation rate. When the rice gels were subjected to non-destructive tomographic analysis, the high amylose rice gels were clearly shown to be favorably fragmented into smaller pieces by chewing, followed by the low and intermediate amylose samples. These results could be explained by their cohesive texture rather than hardness. Therefore, this study may help understanding the changes in the physical properties of cereal-based foods during oral digestion.

국내에서 생산되어 시판되고 있는 보리쌀 제품을 수집하여아밀로오스와 β-glucan 함량을 분석하고 아밀로오스 함량에 따른 찰성 및 메성 보리쌀의 호화 및 취반 특성을 비교하였다.보리쌀 제품은 제품에 표기된 바에 따라 찰보리쌀과 메보리쌀로 분류하여 이들의 아밀로오스 함량을 측정하였다. 분석결과보리쌀 제품의 아밀로오스 함량은 4.46 ~ 30.68% (평균 16.33%)로 다양하게 나타났으며, 찰보리쌀 제품은 대부분 아밀로오스함량이 5 ~ 10% 정도의 분포를 보였다. 보리쌀 제품의 β-glucan 함량은 2.49 ~ 6.79% 범위(평균 4.57%)로 분석되었다.시판 보리쌀 제품을 찰보리쌀(아밀로오스 10% 이하)과 메보리쌀(아밀로오스 20% 이상) 그룹으로 구분하여 각각 선발한보리쌀 제품을 비교하였으며, 찰보리쌀이 메보리쌀에 비해 β-glucan 함량이 약 2% 높게 나타났다. 찰보리쌀은 메보리쌀에비해 신속점도측정기(RVA)에 의한 호화개시온도, 최고점도,trough, breakdown, 최종점도, setback이 낮게 나타났다. 보리쌀의 취반특성에서 시판 찰보리쌀은 메보리쌀에 비해 수분흡수율과 퍼짐성은 높은 반면 용출고형분이 낮았으며, 텍스쳐(경도)는 찰보리쌀이 낮아 보리밥의 취반특성 및 식감이 보다 좋은 것으로 평가되었다.

In order to study the cooking characteristics of four rice cultivars of Seolhyangchal, Baegjinju, Ilpum and Haiami, we investigated the relationship between the textures of cooked rice and their physicochemical properties. Different levels in grain weight. length/width ratio and amylose content were observed among the four rice cultivars. There was no significant difference in the amylopectin chain length distribution among the cultivars. Water absorptions of rice grains during soaking were completed between 30 and 40 min, with Haiami showing the slowest absorption. Significant differences in the viscosity properties of rice flour were found by a Rapid Visco Analyser. Baegjinju with low amylose content had the highest viscosity in paste breakdown. According to the DSC results of rice starches, there were significant differences in the onset, peak and conclusion temperatures of the endothermic peak. Gelatinization enthalpy showed energy content changes between 4.20 and 6.97 J/g, with the lowest change in Haiami. Texture properties of cooked rice were assessed using a Texture Analyzer, which showed that the hardness of cooked rice was decreased with soaking than without soaking. However, this finding was not applicable for Haiami rice.

This study was carried out to build a database system for amylose and protein contents of rice germplasm based on NIRS (Near-Infrared Reflectance Spectroscopy) analysis data. The average waxy type amylose contents was 8.7% in landrace, variety and weed type, whereas 10.3% in breeding line. In common rice, the average amylose contents was 22.3% for landrace, 22.7% for variety, 23.6% for weed type and 24.2% for breeding line. Waxy type resources comprised of 5% of the total germplasm collections, whereas low, intermediate and high amylose content resources share 5.5%, 20.5% and 69.0% of total germplasm collections, respectively. The average percent of protein contents was 8.2 for landrace, 8.0 for variety, and 7.9 for weed type and breeding line. The average Variability Index Value was 0.62 in waxy rice, 0.80 in common rice, and 0.51 in protein contents. The accession ratio in arbitrary ranges of landrace was 0.45 in amylose contents ranging from 6.4 to 8.7%, and 0.26 in protein ranging from 7.3 to 8.2%. In the variety, it was 0.32 in amylose ranging from 20.1 to 22.7%, and 0.51 in protein ranging from 6.1 to 8.3%. And also, weed type was 0.67 in amylose ranging from 6.6 to 9.7%, and 0.33 in protein ranging from 7.0 to 7.9%, whereas, in breeding line it was 0.47 in amylose ranging from 10.0 to 12.0%, and 0.26 in protein ranging from 7.0 to 7.9%. These results could be helpful to build database programming system for germplasm management.

A statistical analysis for 3651 genetic resources collected from China (1,542), Japan (1,409), Korea (413), and India (287) was conducted using normal distribution, variability index value (VIV), analysis of variation (ANOVA) and Ducan’s multiple range test (DMRT) based on a data obtained from NIRS analysis. In normal distribution, the average protein content was 8.0%, whereas waxy type amylose and common rice amylose were found to be 8.7% and 22.7%, respectively. The protein contents ranged from 5.4 to 10.6% at the level of 95%. The waxy amylose and common rice amylose ranged from 5.9 to 11.5%, and from 16.9 to 28.5% at 95% confidence level, respectively. The VIV was 0.59 for protein, 0.64 for low amylose, and 0.81 for high amylose contents. The average amylose contents were 18.85% in Japanese, 19.99% in Korean, 20.27% in Chinese, and 25.46% in Indian resources, while the average protein contents were found to be 7.23% in Korean, 7.73% in Japanese, 8.01% in Chinese, and 8.17% in Indian resources. The ANOVA of amylose and protein content showed significant differences at the level of 0.01. The F-test for amylose content was 158.34, and for protein content 53.95 compared to critical value 3.78. The DMRT of amylose and protein content showed significant difference (p<0.01) between resources of different countries. Japanese resources had the lowest level of amylose contents, whereas, the lowest level of protein content was found in Korean resources compared to other origins. Indian resources showed the highest level of amylose and protein contents. It is recommended these results should be helpful to future breeding experiments.

This study was conducted to characterize the amylose and protein contents of 4,948 rice landrace germplasm using the NIRS model developed in the previous study. The average amylose content of the germplasm was 20.39% and ranged between 3.97 and 37.13%. The amylose contents in the standard rice were 4.99, 18.63 and 20.55% in Sinseonchal, Chucheong and Goami, respectively. The average protein content was 8.17% and ranged from 5.20 to 17.45%. Protein contents in Sinseonchal, Chucheong and Goami were 6.824, 6.869 and 7.839%, respectively. A total of 62% germplasm were distributed between 20.06% and 27.02% in amylose content. Germplasm of 81.60% represented protein content of 6.78-9.75%. The distinguishable ranges of amylose contents according to origin were 16.58-20.06% in Korea, 20.06-23.25% in Japan, 23.25-27.02% in North Korea, and 27.02-37.13% in China. In the protein content, approximately 30% of Chinese resources ranged from 9.75 to 17.45%, whereas less than 10% were detected in other origin accessions. Fifty resources were selected with low and high amylose ranging from 3.97-6.66% and 30.41-37.13%, respectively. Similarly, fifty resources were selected with low and high protein ranging from 5.20-6.09% and 13.21-17.45%, respectively. Landraces with higher protein could be adapted to practical utilization of food sources.

The objective of this research was to develop Near-Infrared Reflectance Spectroscopy (NIRS) model for amylose and protein contents analysis of large accessions of rice germplasm. A total of 511 accessions of rice germplasm were obtained from National Agrobiodiversity Center to make calibration equation. The accessions were measured by NIRS for both brown and milled brown rice which was additionally assayed by iodine and Kjeldahl method for amylose and crude protein contents. The range of amylose and protein content in milled brown rice were 6.15-32.25% and 4.72-14.81%, respectively. The correlation coefficient (R 2 ), standard error of calibration (SEC) and slope of brown rice were 0.906, 1.741, 0.995 in amylose and 0.941, 0.276, 1.011 in protein, respectively, whereas R 2 , SEC and slope of milled brown rice values were 0.956, 1.159, 1.001 in amylose and 0.982, 0.164, 1.003 in protein, respectively. Validation results of this NIRS equation showed a high coefficient determination in prediction for amylose (0.962) and protein (0.986), and also low standard error in prediction (SEP) for amylose (2.349) and protein (0.415). These results suggest that NIRS equation model should be practically applied for determination of amylose and crude protein contents in large accessions of rice germplasm.

아밀로스 함량차이에 따른 배유전분의 이화학적 특성을 파악하기 위해 아밀로스 함량의 차이를 보이는 찰벼, 저 아밀로스, 중간 아밀로스, 고 아밀로스 품종의 외관특성, 화학특성, 호화특성 및 기계적 식미치를 조사하였으며, 그 결과를 요약하면 다음과 같다.1. 시료들의 아밀로스 함량은 6.3%∼30.9% 범위로 아밀로스 함량차이에 따라 4개 그룹 찰벼(A), 저 아밀로스(B), 중간 아밀로스(C), 고 아밀로스(D) 품종군으로 나눌 수 있었으며 각 그룹에 속한 품종들의 단백질함량은 5.8 ~ 7.5%로 품종간 차이가 있었으나 아밀로스 함량에 따라 분류된 그룹간 차이는 없었다.2. 시험재료의 외형적 특성을 보면, 백도는 찰벼 품종군이 가장 높고 저아밀 중간아밀로스 품종군이 가장 낮았다. 현미경도는 고 아밀로스 품종 및 찰벼 품종이 메벼품종과 저 아밀로스 품종보다 대체적으로 낮았다.알카리 붕괴도는 5.2∼6.9의 분포를 보였으며 아밀로스 함량이 증가할수록 붕괴도가 커졌으며, 아밀로스 함량과 알카리 붕괴도 간 매우 높은 양의 상관(r=0.884**)을 보였다.3. 아밀로그램 특성을 살펴보면 저 아밀로스 품종군은 호화개시온도가 중간 아밀로스 품종과 비슷한 반면 최고점도와 강화점도는 높고 최종점도와 치반점도는 낮았다. 고 아밀로스 품종군은 호화개시온도가 다른 품종군에 비해 높고, 최고점도와 최저점도가 매우 낮았으며 최종점도가 상대적으로 높아서 강하점도는 낮고 치반점도는 높은 특성을 보였다.4. 식미관련 이화학적 특성들 간 상관을 살펴보면 아밀로스함량은 알카리 붕괴도와 상당히 높은 양의 상관(r=0.88**)을 Toyo-윤기치와는 높은 음의 상관(r=-0.89**) 나타냈고, 아밀로그램 특성 중에서는 호화개시온도, 치반점도와 유의한 양의 상관을 보이며, 강하점도와는 음의 상관을 나타냈다.

Through the sampling four rice cultivars with differing amylose contents, the relationship between the structural and gelatinization properties of endosperm starches was analyzed. These rice varieties exhibited different chain length distribution ratio within the amylopectin cluster as well as varing amylose levels. The proportion of amylopectin short chains of in Goami cutlivars was higher than the other varieties, whereas the Goami 2 which shows amylose extender mutant properties in the endosperm showed the highest proportion of long chains. In X-ray diffraction analysis of rice starches, the Goami 2 variety displayed a B-type pattern whereas the other varieties were all A-type. Among the cultivars with high and normal rice starch levels, those with the higher amylose contents showed distinctly lower swelling. Goami 2 rice was found to have the highest onset and peak gelatinization temperature from the differential scanning calorimetry results. The four rice cultivars under analysis also showed different rates of hydrolysis by amyloglucosidase. These findings suggest that the composition and chemical structure of the starch content is a major determinant of both the gelatinization and functional properties of rice.

A total of 40 Korean rice cultivars were exposed to high temperature during grain filling stage in the greenhouse condition and changes in head rice ratio of brown rice, whiteness of milled rice, amylose and protein contents were investigated in comparison with field-grown plants. Testing cultivars were categorized into four groups according to maturation period and accumulated temperature was 1216.4～1775.8oC in the field condition and 1275.8～ 1893.7oC in the greenhouse condition during grain filling stage. Reduction ratio of head rice and whiteness under high temperature in the four groups were 23.6, 17.7, 13.0, 8.7% and 12.7, 12.3, 9.5, 6.0%, respectively, in which early-maturing group showed more severe deterioration due to the early exposure to high temperature. Rice cultivar Dongan and Daeya were the most tolerant to high temperature among the tested cultivars showing 0.5 and 6.6% of the head rice reduction ratio and 0 and 1.2% of whiteness reduction ratio under high temperature, respectively. Amylose contents of the four groups were reduced by 11.7, 11.3, 8.8, 8.5% under high temperature in group Ⅰ, Ⅱ, Ⅲ, Ⅳ, respectively, whereas protein contents were increased by 14.2, 6.3, 4.4, 4.4% in the four groups, respectively.